Summary: The main aim of this research work is to develop a model of carbon dioxide (CO2) separation from natural gas by using membrane separation technology. This study includes the transport mechanism of the porous membrane. The fundamental theories of diffusion, poiseuille (viscous) flow, Knudsen diffusion and surface diffusion are used. The developed model of incorporating three diffusion mechanisms to be modified for modeling of polymeric blends towards membrane selectivity and permeability. For the purpose of assessing the gas permeance using the theoretical models, the experimental data taken from CO2 permeance in the PSU/PVAc (85/15) wt. /DEA enhanced polymeric blend membrane was considered. The results obtained from modified Cho Empirical model of total gas permeance showed the least error as compared to other models. The modified Cho Empirical mathematical models were extended by blending factor to predict CO2 gas molecule transport in Enhanced Polymeric Blend Membrane (EPBM) to obtain precise theoretical values that are close to the experimental values. The Extended modified Cho Empirical model validation demonstrated the ability to predict CO2 permeance with reasonable accuracy. © 2019 Chemical Society of Pakistan. All rights reserved.